Neuropeptide regulation of mucosal immunity

Expression of naloxone-resistant beta-endorphin binding sites on A20 cells: effects of concanavalin A and dexamethasone

beta-Endorphin affects mononuclear cell proliferation, cytokine production and calcium uptake in a naloxone-resistant manner. The presence of naloxone-insensitive binding sites for beta-endorphin have been demonstrated on murine EL4-thymoma cells, transformed human mononuclear cells and normal murine splenocytes. Since murine splenic B cells have been shown to express naloxone-resistant receptors for beta-endorphin in response to the mitogen, concanavalin A (Con A), the A20 B-cell lymphoma line was used to further study regulation of this site by Con A and dexamethasone. Analyses showed two sites: a high-affinity site, Kd1 = (8.7 +/- 2.3) x 10(-11) M and binding capacity (Bmax1) of (2.6 +/- 2.0) x 10(3) receptors/cell; and a low-affinity site, Kd2 = (2.2 +/- 0.8) x 10(-8) M with Bmax2 of (1.5 +/- 0.8) x 10(5) receptors/cell. Competition studies showed that N-acetyl-beta-endorphin was approx. 5-fold and beta-endorphin6-31 10-fold less potent than beta-endorphin1-31. Neither beta-endorphin1-27 nor naloxone, morphine or other opioid receptor agonists displaced [125I]beta-endorphin. Con A (20 micrograms/ml) significantly increased the Bmax (3.5-fold; expressed per cell) and resulted in a loss of the higher-affinity site. However, the increased Bmax occurred in proportion to the Con-A-induced increase in protein/cell. Dexamethasone (Dex) also increased Bmax, primarily by increasing (2-3-fold) the number of lower affinity sites. In contrast to Con A, two binding sites persisted after treatment with Dex, which exerted a minimal effect on protein/cell. Therefore, binding/cell and binding/protein/cell were both significantly enhanced by Dex. The combined effects of Dex and Con A on binding failed to show additivity or synergy. When binding was analyzed per protein/cell, the effect of Con A appeared to dominate; the Dex-enhanced binding/protein/cell was no longer evident in the presence of Dex plus Con A. Thus, Dex and Con A may enhance binding by independent mechanisms.

Morphological and functional characteristics of peritoneal mast cells from young rats

To study why neonatal and young rats are resistant to the effects of some secretagogues, such as compound 48/80 and 2.5-S nerve growth factor, we examined peritoneal mast cells from 14-15-day-old rats (young rats) and compared them to peritoneal mast cells from adults. Peritoneal mast cells from young rats contain approximately one-tenth of the amount of histamine observed in adult peritoneal mast cells. However, both cell populations contained similar low levels of the mucosal mast cell-associated protease rat mast cell protease II. Histochemical analysis of peritoneal mast cells from young rats using safranin O and berberine sulphate suggested that only a portion of the granules of these cells contained heparin. At an ultrastructural level the young rat peritoneal mast cell contains relatively few granules. The majority of mast cells from young rats have a bilobed or indented nucleus which is only rarely observed in adult cells. Functionally, the young rat peritoneal mast cell demonstrates a significantly reduced histamine release in response to the connective tissue mast cell-specific secretagogues compound 48/80 and 2.5-S nerve growth factor. In contrast, the percent histamine release in response to the neurotransmitter substance P, which degranulates both connective tissue mast cells and intestinal mucosal mast cells, was similar in the adult cells and the young rat cells. This study demonstrates substantial differences between the young rat and adult peritoneal mast cells which may explain the ability of very young animals to withstand large doses of certain secretagogues.

Lymphoid tissues induce NGF-dependent and NGF-independent neurite outgrowth from rat superior cervical ganglia explants in culture

Induction of neurite outgrowth from superior cervical ganglia (SCG) by rat lymphoid tissues was studied using a tissue culture model. Neonatal rat SCG were cultured with 6-12-week-old rat thymus, spleen, or mesenteric lymph node (MLN) explants in a Matrigel layer, in defined culture medium without exogenous nerve growth factor (NGF). SCG were also co-cultured with neonatal rat heart (as positive control) or spinal cord (SC; as negative control). To determine whether inflammation affects the ability of lymphoid tissues to induce neurite outgrowth, we also examined MLN at various times after infecting rats with Nip-postrongylus brasiliensis (Nb-MLN). In one series of experiments, a single lymphoid tissue explant was surrounded by four SCG at a distance of 1 mm. The extent of neurite outgrowth was determined by counting the number of neurites 0.5 mm away from each ganglion at several time points. Adult thymus and, to a lesser extent, spleen had strong stimulatory effects on neurite outgrowth from SCG after 12 hr or more in culture. For thymus tissue, this was similar to the positive control heart explants. MLN from normal rats had minimal effect on neurite outgrowth; however, Nb-MLN showed a time-dependent enhancement of the neurite outgrowth, maximal at 3 weeks after infection. The relative efficacy of neurite outgrowth induction (heart > or = thymus > or = Nb-MLN > or spleen > or = MLN > or = SC) was confirmed in a second series of experiments where one SCG was surrounded by three different tissue explants. We then examined the role of 2.5S NGF, a well-known trophic factor for sympathetic nerves, in the lymphoid tissue-induced neurite outgrowth. Anti-NGF treatment of co-cultures of SCG and heart almost completely blocked the neurite outgrowth. Anti-NGF also significantly inhibited thymus- and spleen-induced neurite outgrowth, but not as effectively as heart-induced neuritogenesis (93, 80, and 77% inhibition at 24 hr; 86, 70, and 68% inhibition at 48 hr for heart, thymus, and spleen, respectively). On the other hand, anti-NGF inhibited only 8% of neurite outgrowth induced by 3-week post-infection Nb-MLN at 24 hr, and 41% at 48 hr. These data show that several adult rat lymphoid tissues exert neurotrophic/tropic effects. The predominant growth factor in thymus and spleen is NGF, while Nb-MLN produces factor(s) which is (are) immunologically distinguishable from NGF.(ABSTRACT TRUNCATED AT 400 WORDS)

Bombesin, gastrin-releasing peptide, and neuromedin C modulate murine lymphocyte proliferation through adherent accessory cells and activate protein kinase C

Recent data have shown the ability of bombesin-related peptides to stimulate murine macrophage functions. In the present study, we have investigated the effect of bombesin, gastrin-releasing peptide (GRP), and neuromedin C on the proliferative response of lymphocytes from murine axillary nodes, spleen, and thymus. The results show that these neuropeptides at 10(-9), 10(-10), and 10(-11) M concentrations modulate the lymphoproliferative response, stimulating to a small but significant extent the spontaneous proliferation and inhibiting to a great extent the lymphoproliferative response to the mitogen concanavalin A (Con A). This regulation is probably mediated through adherent accessory cells, since their presence for the neuropeptides to produce their effect. The increased interleukin-1 beta production by Con A in cultures of peritoneal macrophages (a model of adherent accessory cells) decreased after the addition of bombesin, GRP, and neuromedin C; this diminution is a possible mechanism for their inhibitory action on the lymphoproliferative response to Con A. In addition, these neuropeptides caused a significant protein kinase C activation in total leukocyte population and T-enriched lymphocytes from axillary nodes, as well as in peritoneal macrophages.

Neonatal capsaicin pretreatment suppresses intramedullary inflammation in adjuvant-induced spondylitis

In order to investigate the proposed involvement of neuropeptides in musculoskeletal inflammation we pretreated rats, in an adjuvant spondylitis model, with capsaicin, a neurotoxin. Immunohistochemistry showed that administration of capsaicin to newborn rats depleted irreversibly the neuropeptide, substance P. Elimination of capsaicin-sensitive fibres by the neonatal injection of capsaicin did not suppress the peridiscitis of rats in which adjuvant spondylitis was induced at 7 weeks of age. However, elimination of capsaicin-sensitive fibres did suppress the inflammation usually seen in the bone marrow. We speculate that this intramedullary inflammation is normally induced or sustained by capsaicin-sensitive fibres.

Therapeutic effect of the D2-dopamine agonist bromocriptine on acute and relapsing experimental allergic encephalomyelitis

We examined the effect of bromocriptine (BCR) treatment on the duration and severity of neurological symptoms of acute experimental allergic encephalomyelitis (EAE), an animal model for demyelinating diseases, particularly multiple sclerosis. To mimic the clinical situation, BCR treatment was started after the onset of clinical signs. Furthermore, the effect of BCR treatment on the course of a chronic relapsing form of EAE was studied. BCR was injected at daily intervals in a dose that resulted in sustained suppression of plasma concentrations of prolactin, a pituitary hormone that plays a role in immunoregulation. In acute EAE, BCR therapy reduced both severity and duration of the clinical signs. In chronic relapsing EAE, BCR treatment did not affect the severity and duration of the first attack, but reduced the duration of the subsequent, second attack. Thus, BCR treatment improves the clinical course in animals with ongoing disease. These findings may have implications for the search for new therapeutic approaches in multiple sclerosis.

Vasoactive intestinal peptide (VIP) inhibits substrate adherence capacity of rat peritoneal macrophages by a mechanism that involves cAMP

In this study, vasoactive intestinal peptide (VIP) is shown to inhibit substrate adherence capacity of rat peritoneal macrophages. The inhibitory response occurred in the 0.1-1,000 nM range of VIP concentrations and it was a time-dependent process. At 15 min, half maximal inhibition (IC50) was obtained at 0.37 +/- 0.26 nM and maximal inhibition (53.8%) at 10(-6) M VIP. The inhibitory effect of VIP was correlated with the stimulation by this peptide of cyclic AMP (cAMP) production in rat peritoneal macrophages. Moreover, agents that inhibited VIP-stimulated cAMP production, such as the VIP-antagonist [4-Cl-D-Phe6, Leu17]-VIP and somatostatin, also decreased the inhibitory effect of VIP on substrate adherence capacity of macrophages. On the contrary, the phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine (IBMX) and the lipid-soluble derivative of cAMP N6,2'-O-dibutyryl cAMP (Bu-cAMP) inhibited the adherence of macrophages to substrate and potentiated the inhibitory action of VIP. These results demonstrate that VIP inhibits substrate adherence capacity of rat peritoneal macrophages by a mechanism that involves cAMP, and show, for the first time, an action of VIP on the function of peritoneal macrophages.

Leukemia inhibitory factor production by rat mast cells

Leukemia inhibitory factor (LIF) is a pluripotent cytokine of importance in the regulation of immune and inflammatory responses. This cytokine may play an important role in neuronal development and bone metabolism. We have examined the ability of freshly isolated rat mast cells and mast cell lines to produce LIF at both the mRNA and bioactivity levels. Initial experiments demonstrated that two mucosal mast cell-like cell lines RBL.2H3 and RCMC9 endogenously produced low levels of LIF bioactivity. The production of this cytokine was examined using a hepatocyte-stimulating factor activity assay and confirmed by the use of neutralizing antibodies specific for LIF. This production was enhanced by treatment with the calcium ionophore A23187. No interleukin-6 production was observed by these cells either endogenously or following ionophore activation. Freshly isolated highly purified rat peritoneal mast cells also expressed mRNA for LIF. These results could have important implications for the role of mast cells in neuronal development, hematopoiesis bone metabolism and the acute-phase response.

Repeated antigen challenge in rats induces a mucosal mast cell hyperplasia

BACKGROUND

A link between mast cells and a number of intestinal diseases has been suggested. Treatment of adult rats with connective tissue mast cell degranulating agents has been shown to induce an intestinal mucosal mast cell hyperplasia. We have examined the hypothesis that repeated systemic antigen challenge would similarly up-regulate the mucosal mast cell population.

METHODS

Animals were primed with 10 micrograms of albumin and challenged twice weekly with 3, 30, or 300 micrograms of ovalbumin, subcutaneously, for 4 weeks. The mast cell numbers were assessed histologically. In addition, measurements were made of tissue/mast cell-mediator content.

RESULTS

Repeatedly challenged animals that received 30-micrograms doses of soluble ovalbumin developed a mucosal mast cell hyperplasia in the duodenum 2 weeks after the cessation of treatment. No change in connective tissue mast cell numbers was observed. Repeated administration of 300 micrograms of antigen did not induce a mucosal mast cell hyperplasia. No significant difference between the mucosal mast cell numbers in antigen-challenged and control animals was observed when animals were treated concurrently with the mast cell-stabilizing agent disodium cromoglycate.

CONCLUSIONS

Repeated antigen challenge at doses that induce mast cell activation is associated with an increase in the number of mucosal mast cells.

Regulation of Langerhans cell function by nerves containing calcitonin gene-related peptide

Several observations suggest interactions between the immune and nervous systems. Psoriasis and atopic dermatitis may worsen with anxiety and have been associated with anomalous neuropeptide regulation. Neurotransmitters affect lymphocyte function and lymphoid organs are innervated. Calcitonin gene-related peptide (CGRP) is a neuropeptide and vasodilator that modulates some macrophage functions, including antigen presentation in vitro. CGRP is associated with Langerhans cells (LC) in oesophageal mucosa, particularly during inflammation, is present in epidermal nerves and is associated with Merkel cells. We examined the ability of CGRP to modulate LC antigen-presenting function and asked if CGRP-containing nerves impinge on LC. We report here that CGRP-containing nerve fibres are intimately associated with LC in human epidermis and CGRP is found at the surface of some LC. In three functional assays CGRP inhibited LC antigen presentation. These findings indicate that CGRP may have immunomodulatory effects in vivo and suggest a locus of interaction between the nervous system and immunological function.

Topography of the enteric nervous system in Peyer's patches of the porcine small intestine

The mechanisms of intercommunication between the immune and nervous systems are not fully understood. In the case of the intestine, the enteric nervous system is involved in the regulation of immune responses. It was therefore decided to employ immuno-histochemical techniques to investigate the structural organization of the enteric nervous system in Peyer's patches of the porcine small intestine. Using antibodies against various nervous system-specific markers (protein gene product 9.5, neuron-specific enolase, neurofilament 200, S-100 protein and the glial fibrillary acidic protein), an intimate and specific structural association could be demonstrated between enteric nerves and the compartments of Peyer's patches: follicles, interfollicular regions and domes. Peyer's patches have a close topographical relationship to the two submucosal plexuses. Enteric nerves are located around the follicle in the interfollicular area--the so-called "traffic area"--and in the dome area, which plays an important role in the uptake and presentation of antigens.

Role of central nervous system and behaviour in the immune response

Recent advances in antigen preparation and delivery have led to a renewed interest in vaccination to control infectious disease. However, relatively less attention has been devoted to host factors which affect the outcome of immune responses. There is now increasing acceptance that the central nervous and immune systems interact, and that this can be a bidirectional process. A range of behavioural and psychological states, learned responses and reactions to external stimuli have all been implicated in immune modulation. These interactions may occur via the direct innervation of lymphoid compartments, by paracrine means through the release of mediators from nerves situated in close proximity to cells involved in immunity, or by neuroendocrine signals in the form of hypothalamic, pituitary and peripheral endocrine hormones. These effects may account to some extent for unexplained variability in response to vaccination and disease challenge, through inherited or acquired differences in neuroendocrine or neurotransmitter responses to stress, circadian effects or learned behavioural responses. This review addresses the effects of environmental stimuli and behavioural manipulations on immune outcome and the response to vaccination, and the potential for practical application of these techniques in human and animal disease control and health management.

Substance P and vasoactive intestinal peptide in nasal secretions and plasma from patients with nasal allergy

To clarify the role of substance P (SP) and vasoactive intestinal peptide (VIP) in nasal allergy, we measured their concentrations in the nasal secretions and plasma of normal subjects and patients with nasal allergy to house dust and Japanese cedar pollen by competitive enzyme-linked immunoassay. The mean levels of SP (224 pmol/L) and VIP (41.6 pmol/L) in the nasal secretions of normal subjects were significantly higher than those in plasma (SP 3.04 pmol/L and VIP 1.04 pmol/L; p < .01). The mean levels of SP and VIP in the nasal secretions of the pollinosis group were significantly higher than those of the control group (p < .05 and p < .01), while the levels of the house dust allergy group were not higher than those of the control group. Intranasal allergen challenge significantly reduced SP levels in the nasal secretions of the allergy groups, while it did not influence VIP levels in the nasal secretions. These findings suggest that SP and VIP are actively secreted into the nose and may play an important role in the allergic reaction on the surface of the human nasal mucosa.

Nerve remodelling during intestinal inflammation

The intestinal mucosa contains a dense nerve network and many inflammatory cells, and these may interact through the exchange of regulatory molecules. Evidence suggests that intestinal mucosal mast cells are innervated, and it is known that the density of this cell type changes significantly in nematode-infected rats. Recent data indicates that rat jejunal mucosal nerves remodel after Nippostrongylus brasiliensis infection, with degenerative and regenerative phases during the acute and recovery stages of inflammation. Seven weeks postinfection there is a net increase in the density and number per villus of mucosal nerves. These changes suggest that mucosal nerves exhibit structural plasticity in inflamed tissues, which must impact on interactions between the enteric nervous system and other mucosal elements in disease.

Somatostatin inhibition of VIP- and isoproterenol-stimulated cyclic AMP production in rat peritoneal macrophages

The dual regulation of cyclic AMP levels in rat peritoneal macrophages incubated with somatostatin, vasoactive intestinal peptide (VIP), and isoproterenol was studied. Somatostatin exerted a non-competitive inhibition of the stimulatory effect of VIP and isoproterenol on cyclic AMP production. In addition, somatostatin inhibited basal cyclic AMP levels. Our results suggest that somatostatin and VIP may modulate the immune response acting, through cyclic AMP, on macrophage functions.

Expression and function of the neural cell adhesion molecule L1 in mouse leukocytes

The neural cell adhesion molecule L1 is a cell surface glycoprotein of the immunoglobulin superfamily which mediates adhesion between neural cells. The possibility that similar cell-cell recognition mechanisms may be shared by the nervous and immune systems prompted us to study the expression and function of L1 in cells of the hematopoietic system. Immunofluorescence analysis using monoclonal L1 antibody revealed that the molecule is expressed in the bone marrow, spleen, and thymus of the mouse. This observation was confirmed by amplifying cDNA derived from these organs by the polymerase chain reaction with L1-specific oligonucleotide primers. Two-color fluorescence analysis indicated that bone marrow lymphoid and granulocyte precursor cells express low and high levels of L1, respectively. In the thymus L1 is primarily expressed by mature cells that have a strong expression of CD3 and in the spleen both B cells and T cells express L1. The possible function of L1 in lymphoid cells was studied using subcloned ESb-MP lymphoma cells having high or low densities of L1 on the cell surface as well as activated splenic B lymphoblasts. Parental and subcloned ESb-MP cells that strongly expressed L1 could form homotypic aggregates in the presence of low Ca2+ levels, whereas subcloned ESb-MP cells with a weak expression of L1 did not aggregate, suggesting that L1 mediates the Ca(2+)-independent aggregation of the parental ESb-MP cells. Furthermore, the aggregation of activated B lymphoblasts under physiological concentrations of Ca2+ and Mg2+ was inhibited by 30% in the presence of Fab fragments of polyclonal L1 antibodies, implying that L1 also mediates adhesion among normal lymphoid cells. A possible role of L1 on lymphocytes in stimulating the innervation of lymphoid organs is discussed.

Ectopic class II major histocompatibility antigens in Hirschsprung's disease and neuronal intestinal dysplasia

Although the etiology of Hirschsprung's disease and neuronal intestinal dysplasia remains obscure, both have histological abnormalities involving ganglion cells and neuronal elements. Searching for a common pathway that may inhibit normal maturation of neurogenic precursors, we examined the possible role of an immune mechanism in the maldevelopment of the enteric neural network. Six patients with Hirschsprung's disease were studied by comparing biopsy specimens from diseased colon with ones taken from proximal ganglionic colon in the same patients. These were similarly compared with colonic biopsy specimens from patients studied with chronic constipation or bowel removed at the time of operation for other disorders. Biopsies were taken from four other patients with neuronal intestinal dysplasia. Each was examined by hematoxylin & eosin staining, acetylcholinesterase histochemistry, and immunohistochemistry of major histocompatibility complex (MHC) class I and class II antigens. All rectal samples from Hirschsprung's disease patients exhibited elevated acetylcholinesterase histochemistry and absent ganglia to confirm the diagnosis. These findings were correlated with marked elevation of class II MHC in the aganglionic area, whereas the proximal normal ganglionic segments showed no elevation. Rectal biopsy specimens from patients with chronic constipation exhibited no such elevation. A similar elevation of class II MHC was detected in the mucosa and submucosa of all four patients with the rare neuronal intestinal dysplasia disorder whose diagnosis was confirmed by giant ganglia in Auerbach's plexuses, aberrant Meissner's ganglia in the lamina propria mucosa, and giant neurofibrils in the mucosa and submucosa. The correlation of elevated class II MHC in these two neuronal dysfunction disorders may indicate an underlying autoimmune mechanism as is seen in thyroiditis and insulin dependent diabetes mellitus.(ABSTRACT TRUNCATED AT 250 WORDS)

Are lymphocytes a target for substance P modulation in arthritis?

The contribution of the neuropeptide substance P to the pathogenesis of rheumatoid arthritis (RA) has recently been suggested. The presence of immunoreactive substance P in the serum and joint fluid of RA patients was significantly increased compared with age-matched control patients. To investigate the ability of substance P to alter lymphocyte activity during the disease, lymphocytes were isolated from the synovial fluid and blood of RA patients and their ability to respond to substance P as measured by [3H]thymidine uptake was characterized. Upon exposure of RA synovial fluid and peripheral blood lymphocytes to various concentrations of substance P in vitro, no increase in proliferation was witnessed. To the contrary, control peripheral blood lymphocyte proliferation was significantly enhanced by various concentrations of substance P. However, synoviocytes from the joints of RA patients were responsive to substance P stimulation. These data suggest that substance P receptors may be desensitized on systemic and local lymphocytes in RA, or the proinflammatory activities of substance P may be mediated via the synovial membrane during chronic inflammation.

Enhancement of antigen-specific T-cell reactivity on the affected side in stroke patients

We have analyzed the impact of stroke with subsequent hemiparesis and sensory loss on in vivo mediated immune functions. The delayed-type hypersensitivity (DTH) reaction to purified protein derivate (PPD, tuberculin) was used as a measure of antigen-specific T-cell reactivity, and subcutaneous immunization with influenza vaccine was employed to evaluate T-cell-dependent B-cell function. Thirty-two of the 50 stroke patients tested displayed positive DTH reaction to PPD. All but two showed equal or stronger DTH reaction on the paretic arm compared to the contralateral side (p less than 0.0001). This stroke-induced enhancement of DTH reactivity was evident in patients with combined motor and sensory deficit as well as in subjects with hemiparesis alone. In contrast, immunization of stroke patients with influenza vaccine, a T-cell-dependent B-cell antigen, raised equal antigen-specific serum IgG, IgA and IgM antibody responses irrespective of side (paretic or not paretic). We conclude that stroke enhances antigen-specific T-cell reactivity on the affected side of the body, and that motor but not sensory deficit seems to be required for this enhancement. Antigen-specific B-cell reactivity was not significantly influenced by the hemiparesis.

The role of autonomic nervous system and inflammatory mediators in nasal hyperreactivity: a review

The last decade has seen a marked increase in the number of otolaryngologists-head and neck surgeons who have been trained to perform rhinologic surgery. This includes both rhinoseptoplasty and endoscopic sinus surgery. A better understanding of the pathophysiology of rhinitis and sinusitis has also kept pace with this rapid expansion of surgical intervention. For example, significant advances have taken place in our knowledge of the local immune system in the nose, particularly in regard to mucosal and submucosal mast cells and the development of protective antibodies in the nasal mucosa against viral and bacterial infections. We have far more understanding of the complex innervation of the blood vessels and glands in the nasal mucosa and their receptors, and, most recently, a tremendous increase of scientific data has accumulated on the effect of neuropeptides on the nasal mucous membrane. It is imperative that rhinologic surgeons have an understanding and appreciation of the complex patterns of sensory and autonomic innervation of the nose to better evaluate the medical, allergic, and surgical treatment of acute and chronic rhinitis and sinusitis. This discussion will focus on recent advances in our understanding of the biochemical substances that are released by both the autonomic nervous system and the sensory nervous system in the nasal mucosa. The effect of these mediators on both vascular smooth muscle and the seromucinous glands of the nose will be considered. Finally, the dynamic interaction between the inflammatory mediators released by sensory nerves so-called tachykinins-- and the immune system and mast cell degranulation will be considered.

Improvement of symptoms of non-allergic chronic rhinitis by local treatment with capsaicin

Sixteen adult patients suffering from severe chronic non-allergic rhinitis with nasal vasoconstrictor abuse for more than a year, received, under local anaesthesia, an intranasal spray of capsaicin (3.3 x 10(-3) mol), the pungent agent in hot pepper, once weekly for 5 weeks. The subjective intensity of their nasal obstruction, rhinorrhoea and sneezing frequency were evaluated throughout the study and the vascular effects of capsaicin on the nasal mucosa were recorded by anterior rhinomanometry and laser Doppler flowmetry. Calcitonin gene-related peptide (CGRP) is a vasodilator agent present in sensory nerves and may play a major role in the vascular component of neurogenic inflammation. Therefore, the nasal mucosa content of CGRP-like immunoreactivity (CGRP-LI) was determined by radioimmunoassay in biopsies obtained before and after the capsaicin treatment. Intra-nasal capsaicin application evoked a larger vascular response in patients with rhinitis than in controls (P less than 0.05). Both nasal vascular responses and subjective discomfort following capsaicin were markedly reduced after the fifth application (P less than 0.01). In parallel, a 50% reduction of the CGRP-LI content in the nasal biopsies was observed. All symptoms were significantly improved throughout a 6 month follow-up period. No significant side-effects occurred and weaning from nasal vasoconstrictor agents was possible. Both the subjective symptom score and objective measurements of vascular reactivity suggest that repeated intra-nasal capsaicin application could be beneficial for patients with chronic rhinitis, possibly by reducing hyperreactive nasal reflexes.

Local immune response and bronchial reactivity in rats after capsaicin treatment

The interaction between the nervous system, immune system and bronchial reactivity was studied in rats by using the neurotoxin capsaicin. Rats were treated with capsaicin at 1-2 days of age or at adult age, before or after sensitization by subcutaneous injections with ovalbumin (OA). The levels of the neuropeptides neurokinin A and calcitonin gene-related peptide were decreased in the lung after capsaicin treatment, as determined with radioimmunoassay, whereas the levels of neuropeptide Y were unaffected. The levels of IgA, IgE and IgG in bronchial lavage were also affected by capsaicin treatment; however, the results were heterogeneous. Capsaicin treatment after sensitization reduced the bronchial reactivity to challenge with OA aerosol and serotonin iv. The results demonstrated that reduction of neuropeptide levels with capsaicin affected both bronchial reactivity and the levels of antibodies in bronchial lavage fluid. However, no correlation between these two parameters was seen, demonstrating the complexity of the system.

The effects of acute and chronic exercise of immunoglobulins

The effects of acute exercise (both graded-maximal and submaximal) and exercise training on resting immunoglobulin levels and immunoglobulin production are reviewed. Brief graded-maximal or intensive short term submaximal exercise tends to be associated with increases in serum immunoglobulins, the pattern of which does not vary between athletes and nonathletes. Plasma volume changes appear to largely explain these acute increases. Acute moderate exercise, such as a 45-minute bout of walking, on the other hand, has been associated with a transient rise in serum immunoglobulin levels despite no change in plasma volume. This increase is probably the result of contributions from extravascular protein pools and an increased lymph flow. Total serum immunoglobulin changes following less than 40 km of running are minor and/or statistically insignificant, although the concentration of IgG is observed to be at its lowest by 1.5 hours after exercise. The greatest effect of acute submaximal exercise appears to be on serum IgM levels which tend to increase, although results are somewhat inconsistent. Various mechanisms of stimulation have been proposed to explain the exercise-induced effect on IgM, which is the first antibody class produced in an immune response. These mechanisms include nonspecific noradrenergic sympathetic neural interactions with the immune system and the possibility of antigen stimulation through greater-than-normal quantities of microorganisms entering the body through both increased ventilation rates and breakdown of natural mucosal immunity by drying of airway secretions. When athletes run 45 to 75 km at high intensities, serum immunoglobulin levels have been reported to be depressed for up to 2 days. Thus intense ultramarathon running may lead to greater and longer lasting decreases in serum immunoglobulin levels than following exercise of shorter duration. IgA and IgG, immunoglobulins commonly found in airway and alveolar space secretions, may have diffused from the serum during recovery from prolonged endurance exercise nonspecifically and/or in response to microbial agents and antigens introduced into the airways during the exercise bout. It has been well established that prolonged endurance exercise is associated with muscle cell damage and local inflammation. It has been hypothesised that natural (IgM) autoantibodies may be used to assist macrophages in disposal of muscle cell breakdown products. This could occur either by IgM binding to breakdown products present in the blood, followed by their clearance from the circulation, or it is possible that these antibodies may leave the circulation to carry out this same function in tissues.(ABSTRACT TRUNCATED AT 400 WORDS)

Immunomodulatory activities of the somatostatin analogue BIM 23014c: effects on murine lymphocyte proliferation and natural killer activity

We have examined the effect of somatostatin and its octapeptide analogue BIM 23014c on concanavalin A-induced lymphocyte proliferation and target-specific natural killer activity both in vitro and in vivo. Using Peyer's patches and spleen as a source of lymphocytes, we found that both peptides modulated immunity in a dose-dependent manner. Comparatively, there was no significant difference between the activity of somatostatin or BIM 23014c in the modulation of immunity. Proliferation, both in vitro and in vivo, was significantly inhibited by both peptides in each organ with a higher specificity towards the Peyer's patch lymphocytes. Natural killer activity was also inhibited in both organs in vivo and in vitro. Thus, not only did somatostatin and BIM 23014c have similar effects on proliferation and natural killer activity, but their effect was organ specific. Preliminary data suggest that BIM 23014c works via the same receptor as somatostatin, therefore intimating that these two peptides are both clinically and immunologically similar.

Neural control of human nasal secretion

Patients with allergic and non-allergic nasal disorders may complain of symptoms of itching, discharge, congestion or fullness, and obstruction of airflow. The actions of sensory nerves and parasympathetic reflexes are central to the development of these symptoms, and likely play crucial roles in allergic and non-allergic nasal pathology. Nasal provocation studies have provided much information about the nature of the processes which contribute to the production of nasal secretions and the development of obstruction to nasal air flow. The results of human nasal provocation studies will be discussed after a review of the special anatomy of the human nasal mucosa, its vasculature, and its innervation.

Neuroendocrine and immunological mechanisms in stress-induced immunomodulation

Here, we report that emotional stressors (restraint, footshock) can affect humoral immune responses as well as the capacity of immune and accessory cells to secrete interleukins. Acute restraint stress (5 min) caused a 4- to 6-fold enhancement of splenic antibody responses to sheep red blood cells. In an attempt to study endocrine mechanisms, we administered antibodies raised in rats to corticotropin releasing factor (CRF). Intravenous administration of these antibodies prior to stress-exposure and immunization prevented the stress-induced increase in the humoral response. In a parallel experiment, we observed that CRF-immunoneutralization prevented the restraint stress-induced increase in plasma ACTH concentrations, but was without effect on plasma prolactin, melanocyte stimulating hormone, adrenaline and noradrenaline responses. These data suggest the presence of an indirect pathway involving ACTH and related peptides by which CRF controls humoral responses to stress. A pathway involving a direct mechanism of CRF at the level of the immune cells will be discussed. In a set of other experiments, we addressed the question of whether interleukin-1 and interleukin-6 plasma levels induced by injection of endotoxin could be modulated by emotional stress. Exposure to prolonged footshock stress (20 min) prior to endotoxin injection resulted in a blunted plasma ACTH and interleukin-1 response, without affecting the endotoxin-induced plasma interleukin-6 response. These data suggest that at least one level at which emotional stress may influence immune function is by changing the capacity of immune cells to produce and/or secrete immune regulatory interleukins.

Effects on immune responses in rats after neuromanipulation with capsaicin

The effect of capsaicin treatment on the immune response, assessed as antibody formation in vivo and in vitro, was studied in ovalbumin (OA)-immunized rates. Rats were treated with capsaicin at 1-2 days of life or at adult age, before or after immunization. The levels of IgA, IgE and IgG antibodies as well as immunoglobulins were measured in serum and supernatants from cultured lymph node cells, spleen cells and peripheral blood lymphocytes. Capsaicin treatment affected the antibody levels depending on the timing of capsaicin treatment in relation to immunization. Different effects of capsaicin treatment were also observed on the different immunoglobulin isotypes. One of the most striking effects by capsaicin treatment was the reduction of IgA and IgG synthesis in cultured lymphoid cells from aerosol immunized animals treated with capsaicin after immunization. In contrast, in vivo the level of total serum IgA was increased in similarly treated animals. In this study we show that capsaicin treatment, which is known to decrease the levels of neuropeptides of sensory origin, has a time-dependent effect on both antibody levels in vivo as well as the formation of immunoglobulin in vitro. Although the mechanisms responsible for this are not obvious, we conclude a link between depletion of neuropeptides in sensory nerves and the antibody synthesis.

Substance P innervation of the rat thymus

Immunohistochemistry for substance P (SP) in the rat thymus revealed fine varicose neural profiles in specific regions of the thymus. Thymic SP innervation was abundant within the capsule and interlobular septa. The majority of SP+ nerve fibers within the septa were free of vascular association, although some fibers were associated with the vasculature deep within the septa. SP+ nerve fibers entered the thymic cortex from the septa and distributed among cortical thymocytes and mast cells. Along the corticomedullary junction, SP+ nerve fibers were found in association with the vasculature. The medullary region of the thymus received only a sparse innervation of SP+ fibers. In addition, SP+ nerve fibers coursed adjacent to OX-8+ cells and mast cells in the extrathymic connective tissue surrounding the thymus. The present study provides evidence that SP is present in nerve fibers in the thymus, and may be available to interact with thymocytes, mast cells, and other cells in the thymus, and affect their development and function.

Peptidergic innervation of rat lymphoid tissue and lung: relation to mast cells and sensitivity to capsaicin and immunization

The peptidergic innervation of lymphoid tissue and the lung in relation to mast cells was studied in rat. The sensitivity of neuropeptide-containing nerves to capsaicin treatment and immunization was also examined. Measurements of the content of neurokinin A and calcitonin gene-related peptide revealed that the lung contained the highest content of both neuropeptides; lymph nodes had intermediate levels, whereas the spleen had the lowest content. Immunohistochemistry showed that the calcitonin gene-related peptide- and neurokinin A-immunoreactive nerves in lymph nodes were mainly found around blood vessels, whereas in the lung the nerves were present within the lining respiratory epithelium, bronchial smooth muscle, around blood vessels and close to lymphoid aggregates. Combined immunohistochemistry for serotonin (5-hydroxytryptamine), as a marker for mast cells, and tachykinins or calcitonin gene-related peptide revealed that a close association was often present between the nerves and 5-hydroxytryptamine-positive cells in the bronchi of the lung, while 5-hydroxytryptamine-positive cells were not observed in lymph nodes. The neurokinin A and calcitonin gene-related peptide content in lymph nodes, spleen and lung, but not the content of neuropeptide Y, was markedly decreased by capsaicin treatment, suggesting a sensory origin for the two former peptides. Aerosol immunization increased the levels of calcitonin gene-related peptide in the lung, whereas the content in mediastinal lymph nodes was not affected. These data demonstrate a peptidergic innervation mainly of blood vessels in lymphoid tissue and a close relation between sensory nerves and mast cells as well as lymphoid aggregates in the bronchi of the lung.(ABSTRACT TRUNCATED AT 250 WORDS)

Gastrointestinal neuropeptides suppress human colonic lamina propria lymphocyte DNA synthesis

Gastrointestinal neuropeptides have been shown to modulate the circulatory immune system, but their effect on the mucosal immune system is not well defined. We studied the effect of VIP, SOM, S-P and Bomb on thymidine incorporation into human colonic lamina propria lymphocyte (LPL) DNA. Physiologic concentrations of VIP, SOM, S-P and Bomb significantly suppressed thymidine incorporation into Con A-stimulated human LPL. These neuropeptides did not affect DNA synthesis when LPL were induced with phorbol ester (PDB) and calcium ionophore (ionomycin). Our data suggest that a) VIP, SOM, S-P, and Bomb may have a regulatory role in the human mucosal immune system, and b) Bomb should be added to the list of neuropeptides which affect the gut immune system.

Prenatal alcohol exposure alters the development of sympathetic synaptic components and of nerve growth factor receptor expression selectivity in lymphoid organs

Exposure to alcohol in utero has been associated with long-term immune deficits. In addition, adult mice exposed to alcohol prenatally display altered noradrenergic synaptic transmission selectively in lymphoid organs. This is consistent with the hypothesis that sympathetic neurons play an important role in immunomodulation. The development and maintenance of sympathetic neurons are critically dependent on nerve growth factor (NGF). Furthermore, NGF has been shown to modulate immune responses and NGF receptor expression has been localized to lymphoid organs. The present work examined the effects of prenatal alcohol exposure on the development and maturation of pre- and postsynaptic sympathetic components, including norepinephrine and beta-adrenoceptors, respectively, as well as the early expression of NGF receptors in lymphoid and other organs of the C57BL/6 mouse. Infant mice that were exposed to alcohol in utero displayed reduced levels of norepinephrine and beta-adrenoceptor density, as well as increased NGF receptor expression in the thymus and spleen, but not the heart. These selective changes may account, in part, for the persistent immune incompetence characteristic of fetal alcohol syndrome.

Activation of rat peritoneal mast cells in coculture with sympathetic neurons alters neuronal physiology

Rat peritoneal mast cells (PMC) were activated with anti-IgE or 48/80 while in coculture with neurons dissociated from mouse superior cervical ganglia. At 18-24 h of coculture, microelectrode recordings from neurons were made 15 min after activation of PMC with anti-IgE antibody or the secretagogue compound 48/80. These recordings showed that PMC activation caused depolarization of the neurons and decreased their membrane resistance. Both methods of activation resulted in similar changes in these neuronal characteristics. The resting potential decreased by an average of 15% from the control value of -36.0 +/- 0.6 mV (SEM) (n = 121). The membrane resistance decreased by an average of 60% from the control value of 34.2 +/- 2.0 M omega (n = 75). Application of PMC secretion products directly onto neuronal somata caused reversible changes similar to those caused by activation of cocultured PMC. A decrease in membrane resistance that was observed in neurons cocultured with PMC for 18-24 h without stimulation was due to a proportion of PMC undergoing spontaneous activation. These changes in neuronal physiology are attributed to the action of substances released from the mast cells. This coculture model offers the means to study the cellular interactions involved in neuroimmune communication.

Effects of stress on the immune system

Stress, distress and a variety of psychiatric illnesses, notably the affective disorders, are increasingly reported to be associated with immunosuppression. The concept that psychic distress may predispose to medical illness is centuries old but has only recently attracted the attention of the scientific community at large. Interdisciplinary collaboration has established psychoneuroimmunology, or neuroimmunomodulation, as a new field of investigation with the goal of rigorous scientific research into the elusive mind-body connection. This has resulted in the rapid accumulation of information which falls across the boundary lines of psychiatry, immunology, neurosciences and endocrinology. Here David Khansari, Anthony Murgo and Robert Faith review the effects of stress on the endocrine and central nervous systems and the interactions between these systems and the immune response after exposure to stress signals.

Neuroimmunomodulation of in vivo anti-rotavirus humoral immune response

Neuropeptides and neurohormones (neurotransmitters) have been shown to modulate immune responses in vitro and in vivo. Since reproduction and lactation are regulated by neurohormones, we investigated whether neurohormones could enhance anti-rotavirus immunity in milk. Rotavirus-free mice were immunized orally with killed bovine rotavirus (BRV) and bred 6 weeks post-immunization. Post-whelping, each group of dams (ten mice/group) was given a single injection of prolactin (PRL), estrogen, PRL and estrogen or testosterone. The effects of neuropeptides, substance P (SP) and somatostatin (SS) on serum and lactogenic anti-rotavirus humoral immune responses were also investigated. The results revealed that in the groups given PRL or estrogen, anti-rotavirus antibody titers in milk and serum were enhanced. In contrast, testosterone had a negative effect on antibody titers. The administration of neuropeptide SP resulted in some enhancement of the lactogenic anti-rotavirus antibody titer at day 9 post-whelping whereas the opposite effect was observed following administration of SS. Prolactin given at 100 micrograms/mouse, on the day after whelping, gave optimum milk and serum antibody responses. Neurotransmitters potentiated immune responses to the weaker immunogenic proteins, VP4 and VP7 as well as to the strongly immunogenic VP6. In order to verify that the enhancement of anti-rotavirus antibody production was due to PRL and not to other factor(s), bromocriptine (BCR), a selective PRL inhibitor, was used as a control. Mice given BCR exhibited a drastic reduction in anti-rotavirus antibody in serum and milk. The role of neurotransmitters in the modulation of the lactogenic immune response and its significance in protection of neonates from enteric infections is discussed.

Accumulation of CD8+ cells after immunization with soluble antigen

Rats were immunized with ovalbumin, either subcutaneously or by aerosol inhalation. The lymphocyte distribution in lymph nodes, peripheral blood, and spleen was investigated by flow cytometry after labelling with T pan (OX19 and W3/13), T helper lymphocytes (W3/25), T cytotoxic/suppressor lymphocytes (OX8), kappa light chain (MAR 18-5), or MHC class II (OX6) monoclonal antibodies. The influence of the neurotoxic agent capsaicin on the lymphocyte distribution was also analysed. Subcutaneous immunization resulted in an increased number of OX8+ cells in mesenteric lymph nodes, spleen, and peripheral blood but not in the draining lymph nodes, axillary, brachial, and mediastinal lymph nodes. The number of positive cells for the other cell markers used were not affected by immunization. The neuromodulatory effect of capsaicin had no effect on the lymphocyte distribution. The results showed that the type of immunization used, low amounts of antigen without adjuvant given during a prolonged period, selectively induced OX8+ cells. The patterns were unaffected by neuromodulation using capsaicin.

Differential effect of opioids on immunoglobulin production by lymphocytes isolated from Peyer's patches and spleen

The mucosal immune system plays an important role in blocking the penetration of invasive organisms into various mucosal surfaces. Evidence now suggests neuroendocrine peptide hormones have immunomodulatory properties, including the ability to alter mucosal immunity. The potential for opioid compounds and corticotropic hormone (ACTH) to modulate mucosal immune function was investigated. We have found beta-endorphin, ACTH, and naltrindole (delta-class opioid receptor antagonist) to significantly suppress concanavalin A-stimulated Peyer's patch lymphocyte immunoglobulin production of IgA, IgG, and IgM isotypes. Oxymorphindole, a delta class opioid receptor agonist, significantly decreased IgM but not IgA or IgG production by the mitogen-stimulated Peyer's patch lymphocytes. Both oxymorphindole and naltrindole modestly reduced interleukin-2 receptor expression of concanavalin A- (Con A)-stimulated splenic and Peyer's patch lymphocytes. Neither compound appreciably affected immunoglobulin production by lipopolysaccharide-stimulated Peyer's patch lymphocytes. Collectively, these results indicate stress-related peptides such as ACTH and opioids may be involved in the regulation of immunoglobulin synthesis by Peyer's patch lymphocytes.

Expression of nerve growth factor receptors by human peripheral blood mononuclear cells

In the rat, nerve growth factor (NGF) has been shown to affect immune reactivity by binding to cell surface receptors on a subpopulation of splenic mononuclear cells. This binding occurs in a specific and saturable fashion to what appear to be low-affinity (type II) NGF receptors (NGFR). Immunofluorescence studies here showed that NGFR are also present on a proportion of human peripheral blood mononuclear cells (PBMC). Equilibrium binding studies demonstrated that the binding of NGF to its receptors on PBMC occurs with a single equilibrium binding constant (mean) of 2.11 X 10(-9) M. The number of receptors per cell was determined to be approximately 6.94 X 10(3) receptors/cell. These results would suggest a role for NGF in the regulation of immune function in man, as well as in animals.

Novel cellular interactions and networks involving the intestinal immune system and its microenvironment

The interactions we have described enable the intestine to respond appropriately to antigenic challenge in an effective and coordinated way. This is of vital importance when one considers the dual role of the intestine as a first line of defence against harmful microorganisms and as the route by which the animal obtains nutrition. Under normal circumstances, these interactions select for an appropriate cell phenotype by providing a network of interactions that contribute to intestinal homeostasis. If there is dysfunction of any component, then other cells will be affected. For example, if down-regulation of the mucosal immune response is not effective, damage to the epithelium, nerves and muscle may occur during an inflammatory response. Similarly, if the integrity of the epithelium is disrupted, damage to the elements of the mucosal immune system may occur. This model would suggest that these interactions must be considered if one wishes to adequately explain diseases such as IBD and design innovative therapeutic regimens. Future interdisciplinary research will shed light on the web of interactions occurring in the intestinal environment and provide a novel view of the respective contributions of the immune system and its local environment to cell differentiation, function and regulation.

Short-term somatostatin infusion affects T lymphocyte responsiveness in humans

Peripheral blood lymphocytes (PBL) function was analysed in 16 young men with duodenal ulcers after one-hour intravenous infusion of somatostatin (SMS) at a dose of 250 micrograms/h. Proliferative responses of PBL from SMS-treated patients were significantly diminished compared with pre-treatment values, after stimulation with PHA, PWM or Con A. Spontaneous IL-2R expression was moderately increased after SMS infusion but PHA-induced IL-2R expression was not affected by this drug. Alloantigen and autoantigen stimulation of PBL showed no significant changes in the proliferative response after SMS infusion. NK cell activity was similarly unaffected. These observations establish a link between SMS exposure and possible development of immune dysfunction.